"Secret" Labyrinth of Tunnels under Rome Mapped

Deep under the streets and buildings of Rome is a maze of tunnels and
quarries that dates back to the very beginning of this ancient city.
Now, geologists are venturing beneath Rome to map these underground
passageways, hoping to prevent modern structures from crumbling into the
voids below.

In 2011, there were 44 incidents of streets or portions of structures
collapsing into the quarries, a number that rose to 77 in 2012 and 83 to
date in 2013. To predict and prevent such collapses, George Mason
University geoscientists Giuseppina Kysar Mattietti and scientists from
the Center for Speleoarchaeological Research (Sotterranei di Roma) are
mapping high-risk areas of the quarry system.

The mapping is important, Kysar Mattietti told LiveScience, because
through the years, Roman citizens have taken the patching of the quarry
systems into their own hands....